Greetings forum members,
I would like to design a circuit to test the shutter speed on my old film cameras. There are a multitude of circuits available on the web detailing how to use a phototransistor and a battery to output a voltage spike, which can be read on your computers sound card. I have tried this, and the result is satisfactory. I would like to improve on the circuit a little, and I am asking for some advice.
The circuits that I have found allow the phototransistor to operate in its simplest form, just varying the voltage from low to high in response to light. This, combined with a capacitor sometimes, creates a tiny voltage spike that can read when the transistor first sees light, and again when it stops seeing light. I would like to use a photo sensor to trigger a voltage rise for the entire time the sensor sees light. And, I would like it to respond when the sensor sees ANY light, meaning a very, very low threshold. And, I would like it to have very fast response time. The camera shutters that I am testing are not generally faster than 1/1000th of a second, but I do have some cameras that are faster than that.
What should be used, a photodiode, or a phototransistor?
How can either be designed in a circuit to act as a binary switch?
If another transistor is used to make it act like a switch, will the response time be slowed down?
Thank you for any and all suggestions.
Cheers, Josh
I would like to design a circuit to test the shutter speed on my old film cameras. There are a multitude of circuits available on the web detailing how to use a phototransistor and a battery to output a voltage spike, which can be read on your computers sound card. I have tried this, and the result is satisfactory. I would like to improve on the circuit a little, and I am asking for some advice.
The circuits that I have found allow the phototransistor to operate in its simplest form, just varying the voltage from low to high in response to light. This, combined with a capacitor sometimes, creates a tiny voltage spike that can read when the transistor first sees light, and again when it stops seeing light. I would like to use a photo sensor to trigger a voltage rise for the entire time the sensor sees light. And, I would like it to respond when the sensor sees ANY light, meaning a very, very low threshold. And, I would like it to have very fast response time. The camera shutters that I am testing are not generally faster than 1/1000th of a second, but I do have some cameras that are faster than that.
What should be used, a photodiode, or a phototransistor?
How can either be designed in a circuit to act as a binary switch?
If another transistor is used to make it act like a switch, will the response time be slowed down?
Thank you for any and all suggestions.
Cheers, Josh